On the Performance of Two Cells Systems with Adaptive Beamforming and Delay Feedback

In this paper, the influence of feedback channel delay on system throughput of the cooperative multi-cell system with adaptive beamforming selection is discussed. On the one hand, multi-cell cooperative processing (MCP) has the potential to boost spectral efficiency and improve fairness among users. However, the traditional centralized multi-cell cooperative scheme, where a central processing unit is assumed with the global knowledge of all the required downlink channels and user messages to jointly design the transmitted signals for all BSs, incurs significant overhead and complexity, and will hinder the practical implementation of MCP. We adopt the decentralized cooperative scheme with adaptive linear pre-processing transmission. The objective of the scheduling is to maximize the total system throughput. On the other hand, transmit beamforming as a simple yet efficient technique can exploit the benefits of multiple transmit antennas provided that the instantaneous channel state information (CSI) is known at both sides of transmission link. In order to have such improvements, the CSI at both link ends must be updated timely. However, the updating process is always subject to non-ideality such as feedback delay and estimation error, which destroy the performance. The performance of proposed scheme in terms of the average throughput per cell. The multiuser diversity gain is also investigate throughput simulation. Simulation results show that The performance of a multicell cooperative transmission strategy is highly dependent on the quality of the CSI.